LAS VEGAS — Sen. John Ensign (R-Nev.) will announce Monday that he is retiring from the Senate when his current term ends in 2012, media outlets reported.

Ensign, a two-term Senator, called a news conference according to Roll Call at the Lloyd George Federal Courthouse in Las Vegas to take place at noon PT “to discuss his political future in the United States Senate.”

Ensign was facing a tough political environment after admitting to an affair with the wife of a former staffer in 2009.

With his retirement, Ensign will become the eighth sitting senator — and the third Republican — to retire in 2012.